1. Field of the Invention
This invention relates to an electrical accessory device controller system for a motor vehicle and a process for its operation. More specifically, the invention relates to a motor vehicle power supply monitoring and controlling system for protecting a motor vehicle battery from being exhausted by a motor vehicle electrical accessory device.
2. Description of Related Art
U.S. Pat. No. 5,764,469 discloses an apparatus for protecting devices in a vehicle from voltage spikes and preventing the electronic devices from discharging a vehicle battery. The apparatus includes a power supply control unit for the electrical devices wherein the control unit is made such that three predetermined threshold values of a motor vehicle battery voltage are detected. When it is detected that the first threshold value is not reached, a warning signal is output to the vehicle""s operator; and, when the second, lower threshold value is not reached, the electrical devices are disconnected from the motor vehicle battery, in order to prevent exhaustive discharge thereof and to ensure startability of the motor vehicle. Re-connection of the electrical devices takes place when it is detected that a third threshold value which is higher than the first and the second threshold value is exceeded.
Other systems, in which exhaustive discharge protection of the motor vehicle battery is accomplished by monitoring the battery voltage and optionally shutting off electrical devices when given threshold values are not reached, are known, as shown, for example, in published European Patent Application EP 0 636 520 A1 and U.S. Pat. No. 5,691,619.
U.S. Pat. No. 5,693,986 discloses exhaustive discharge protection for a vehicle battery, in which electrical loads, which remained on after the operator has exited the vehicle, are disconnected from the battery.
U.S. Pat. No. 5,929,604 discloses exhaustive discharge protection for a vehicle battery in which a mobile phone system powered by a vehicle battery is turned off when the measured power consumption of the telephone system over time has exceeds a given threshold value. The telephone system is turned on when a power flow to the vehicle battery from the motor vehicle""s alternator is established.
Published German Patent Application DE 195 17 742 A1 discloses a power supply for a motor vehicle in which there are a starter battery and a separate supply battery. Exhaustive discharge protection for both batteries is accomplished by monitoring the respective battery voltage, and when the respective battery voltage drops below a predetermined threshold value, the corresponding battery being separated from the consumer electrical system or the vehicle electrical system.
It is an object of this invention is to provide device for a motor vehicle and a corresponding process for operation thereof which, on the one hand, accomplishes exhaustive discharge protection of the vehicle battery, and on the other hand, enables an operating time of the motor vehicle""s electrical accessory devices as long a possible without the motor vehicle""s alternator running.
In an embodiment of the present invention, by providing an auxiliary power storage device for the motor vehicle electrical accessory devices in combination with monitoring of the voltage of the vehicle electrical system, the disconnecting of the electrical accessory devices from the vehicle battery takes place when given threshold values of the voltage of the vehicle electrical system are reached. On the one hand, exhaustive discharge of the vehicle battery, which can entail shortening of the battery service life and starting problems, can be avoided, and on the other, the auxiliary energy storage device prolongs the operating duration of the electrical accessory devices without harmfully depleting the vehicle battery and, hence, protects the vehicle battery. The latter is accomplished especially in that, after a first threshold value of the voltage of the vehicle electrical system is reached, the power to the electrical accessory devices is provided from the auxiliary energy storage device and subsequently from the vehicle battery for a predetermined period of time.
The electrical accessory device in an embodiment of the invention is an auxiliary heating device, and a remote control for controlling battery shut-off timings is preferably a wireless data transmission means, especially a means according to a mobile telecommunication standard, and/or a control device for the auxiliary heating device.
The invention is further described below using several embodiments shown in the drawings.